1. Field of the Invention
This invention relates to an ignition coil device for an internal combustion engine which supplies high voltage to ignition plugs for an internal combustion engine.
2. Discussion of Background
FIG. 5 is a diagram showing the construction of an ignition coil device and a control unit, wherein reference numeral 1 designates an ignition coil device having three sets of ignition coils 1a, reference numeral 2 represents a control unit having three sets of power transistors 21 for interrupting primary current to the ignition coils 1a and three sets of current flowing time setting circuits 22 for controlling the power transistors 21, reference numeral 3 represents lead wires for electrically connecting the ignition coil device 1 and the control unit 2, and numeral 4 designates ignition plugs mounted on respective cylinders (6 cylinders) for an internal combustion engine, not shown.
In the above construction, first, primary current flows in the ignition coil 1a by switching on the power transistor 21 by the current flowing time setting circuit 22 at a predetermined starting time. Next, the power transistor 21 is switched off by the current flowing time setting circuit 22 at a predetermined ignition timing thereby cutting off the primary current in the ignition coil 1a. At this moment, high voltage is generated on the secondary side of the ignition coil 1a, the high voltage is supplied to the ignition plug, and a mixture in a cylinder, not shown, is ignited.
The conventional ignition coil device and control unit are constructed as above, wherein the ignition coil device 1 and the control unit 2 are separately installed. Accordingly, it is necessary to connect the ignition coil device 1 and the control unit 2 through the lead wires 3, and therefore, the lead wires 3, terminals or connectors for connecting the lead wires 3 and the ignition coils 1, and terminals or connectors for connecting the lead wires 3 and the control unit 2 are necessary. Hence, there is a problem in the conventional technology, wherein the number of parts is large, the construction is complicated, and the device is devoid of the mounting performance to an engine or the like. Further, many kinds of control units are necessary for corresponding to internal combustion engines having different number of cylinders, detracting from general purpose use.